2.代码：

#ifndef GRAPH_H#define GRAPH_H class Graph {    public:        Graph(char ch, int n);           void draw();         private:        char symbol;        int size;};#endif

#include "graph.h" #include 
     
      using namespace std;Graph::Graph(char ch, int n): symbol(ch), size(n) {}void Graph::draw() {    for (int i = 0; i < size; i++) {        for (int j = i; j < (size-1); j++)        {cout << " ";}        for (int j = 0; j < i; j++)                {cout << symbol;}        cout << symbol;        for (int j = 0; j < i; j++)                {cout << symbol;}        for (int j = i; j < (size-1); j++)        {cout << " ";}        cout << endl;    }}
     

#include 
     
      #include "graph.h"using namespace std;int main() {    Graph graph1('*',5), graph2('$',7) ;      graph1.draw();     graph2.draw();     int a;    if (cin >> a) {        return 0;    }}
     

结果：

3.代码：

class Fraction{    public:        Fraction(int a=0, int b=1);        void compare(Fraction &p);        void add(Fraction &p);        void subtraction(Fraction &p);        void multiplication(Fraction &p);        void division(Fraction &p);        void reduction();         void show();    private:        int top;        int bottom;};

#include
     
      #include"fraction.h"using namespace std;Fraction::Fraction(int a, int b):top(a),bottom(b){}void Fraction::compare(Fraction &p){    if(p.top>top){        cout<<"前者
      <后者">
       <
       
        =后者"<
       
      
     

#include
     
      #include"fraction.h"using namespace std;int main() {    int m,n,x,y;    cout<<"分数1：";    cin>>m>>n;    Fraction a(m,n);    a.show();    cout<<"分数2：";     cin>>x>>y;    Fraction b(x,y);    b.show();    a.compare(b);    char input;    cout<<"输入+ - * %:";    cin>>input;    switch(input){        case '+':            a.add(b);            break;        case '-':            a.subtraction(b);            break;        case '*':            a.multiplication(b);            break;        case '%':            a.division(b);            break;    }    a.reduction();    a.show();    return 0;}
     

结果

 

负数的计算没能想出来.